From marketplace to infrastructure: taking on new challenges in the development of Mercari and Merpay

Since its founding eight years ago, Mercari has been continuously developing the UX of one app. It’s a development process that has brought them into unexplored territory. But they’re still not finished exploring.

They are aiming to create a new experience by integrating Mercari and Merpay. We asked Yui Yokota, a product manager at Mercari, and Mayumi Narisawa, a product designer at Merpay, to give a behind-the-scenes look into Mercari’s product development.

※This article is a repost from Newspicks

Featured in this article


  • Yui Yokota

    Mercari, Inc. Product manager. Joined Mercari in 2017. After working as a product owner and designer of new businesses, she currently serves as a product manager of Mercari’s Japanese businesses.


  • Mayumi Narisawa

    Merpay, Inc. Product designer. In charge of the UI/UX design for many new businesses at DeNA. Later, she worked on the UI/UX of the physical card and new functions at Kyash. She currently is promoting product design that integrates the experience of payment, credit, and crypto assets in the Mercari app as a product designer and design manager at Merpay.


All for one app, one app for all

──Tell us about your role in Mercari’s product development.

Yokota: My role as Mercari’s product manager is to create a UX from the customer’s perspective. Mercari has professionals in different areas: UX researchers, analysts, engineers. My role is to stand in the middle of them and bring all their work together into a single user experience. I’m committed to improving the quality of the customer experience.

Narisawa: Like Ms. Yokota, I also develop products from the customer’s perspective, and my role as a product designer at Merpay is to visualize new customer experiences.

But unlike Mercari, Merpay is still in its growth stage. We’re having to create something new. We’re trying to smoothly connect Mercari and Merpay’s experiences in the app, while at the same time developing new functions. Right now Merpay is running with these two goals in mind.

I’m a designer, but creating an image is really the last task. I spend a lot of time talking with other members about what customers expect while looking at the screen. We only start working on the screen design once we’ve agreed on the sort of environment that we want to create.

Yokota: As a project leader, dialogue is especially important. If we can’t persuade our colleagues and get on the same page and move forward with a positive attitude, we can’t create the sort of world we have in mind.

It seems to me that Nari-san (Ms. Narisawa) not only creates a lot of visuals and UI as a designer, but also communicates with colleagues to make the entire development process smoother.

──Mercari already has many users and has become known as a very “Japanese” app. What’s special about the product development that you do?

Narisawa: We’re developing Mercari and Merpay as one service. I feel like that’s our unique position—we’re insistent on developing them as a single product.

A flea market is a place where things are bought and sold, so money is indispensable. Merpay backs up the money part, so we’re trying to provide customers with a smooth experience of exchanges physical objects and money.

There used to be an event at Merpay called the “prophecy meeting” where we suggested services and ideas that the company would set up next, like a hackathon. Our CEO, Shintaro (Yamada) served as the judge at these meetings.

At one of these meetings, my team suggested making Merpay an independent app, but Shintaro’s judgment was that making it one app would make it easier for customers to use, with less wasted costs involved. There is a brush-up time during the second half of the prophecy meeting, so that’s when we suggested an experience that integrates Mercari and Merpay as one product. I still remember the positive reactions we got from many of the participants that day.

That’s one of the reasons why we set up a team to integrate Mercari and Merpay.

Yokota: Nari-san and I worked on a project together as part of the fusion team. We originally thought that both Mercari and Merpay could provide a new kind of experience.

Mercari has a very open culture, and the Slack channel is basically open to the public, so when I took a peak at the Merpay thread I thought, maybe they are thinking the same thing. That’s one of the reasons why we decided to put together a team.

Narisawa: From there we started integrating Mercari and Merpay.

Up to this point, all functions related to Merpay were collected together in the Merpay tab, but we changed it so that customers could check how much they had made in sales when they visited their My Page and gave them different ways to increase it.

In other words, we set a goal in our UX to let customers naturally engage with Merpay while using Mercari’s flea market, without being aware of which functions were controlled by Merpay.

When people from different parts of the company collaborate on one app, we can look at the results from different angles, so there’s always room to improve the UX. That’s characteristic of Mercari’s product development strategy, I think.

Collaboration gives us more criteria for evaluating our work, and of course we can also deepen our own expertise in the businesses we’re in charge of. But at the same time, we also get to learn from the expertise of other members who are working to promote other businesses within the same app.

Yokota: What I find so interesting about Mercari is the way we keep questioning our assumptions.

While we are developers, many of us are also users, so in that sense, it’s easy for us to become critics. It’s good to have opinions and feelings as a user, but there is also a risk of believing them too much.

It’s also important to look at the research data and analysis objectively and realize that what your own beliefs are not always accurate.

Learning to formulate a hypothesis based on facts and put it into practice without being influenced by my own personal impressions and feelings, that’s a skill I was able to develop at Mercari.

──It seems like the Mercari app is already been complete. Is there still room for improvement?

Yokota: As an organization, we have this attitude that if we’re not constantly improving the product, it’s over, because it’s really just one product.

And because it’s one product, we can think about how the product can lead to our customers’ happiness down the line. But at the same time, there’s an understanding that the product must continue to grow at all costs.

Narisawa: There’s no sense of, “okay, we’ve reached this point, we’re done.” A UX that was the right answer one day could be completely overturned the next day when our assumptions change. So we have to keep trying new things.

Make a hypothesis, put it into words, rinse and repeat

──For an app with as many users as Mercari has, one change could have a major impact. How do you make decisions?

Yokota: What’s important to us is whether we have a hypothesis in mind as the basis.

We have all kinds of people checking the veracity of our hypothesis and brushing things up along the way.

Narisawa: The point of making a good hypothesis is so that everyone can see what we’re thinking and what we’re trying to do, and it’s also a way to build up our ideas to the point where we can be satisfied with them. It doesn’t matter if it’s a little sloppy or uncool, what matters is that we put it into words and visualize it, and repeat this process of communication in collaboration with our members.

Yokota: Right.

Narisawa: After all of that, we have a spec review with our engineers, and we’re asking whether the thing we’re doing is going to actually change the customer’s experience, up to the very end. “Why did you decide to do it this way?” Down to the last detail.

That is why we have to put all our decisions into words.

Yokota: In the process of verbalizing our ideas, the context gets stripped away, and it becomes clearer what kinds of results we’ll get by making this kind of a decision.

It’s more about clarifying the logic rather than finding the perfect way to express those ideas.

Narisawa: As a result, you gradually start to understand what kinds of messages are easier to convey. Like, at the very least, we’ll be fine as long as we convey this point. It makes everything easier.

Yokota: Right, right. I always think, “What Nari-san said today really hit me!” (laughs).

──I’ve heard that Mercari is made up of a very diverse group of people. Isn’t that a barrier to verbalizing your ideas?

Yokota: Right, well, around half of the engineering organization at the Tokyo office are English speakers. So we use a mix of Japanese and English when we’re communicating our ideas. But more than the simple difficulty of translating our thoughts, we have difficulty understanding the context others are coming from.

There are a lot of things that you’ll understand in a high context environment if you were born and raised in Japan, for example. Our members from overseas often question why we need things to use certain specifications.

Because they trust us, they’ll often tell us that they’ll respect our view, so long as there’s a hypothesis to back it up. But in order to really understand each other and make something great, we need to be able to communicate in a low-context way.

It’s very important to express things in a low-context way so that they can understand what we’re trying to say, even if our social and cultural backgrounds are different.

The outcome at the end is worth it.

A culture of honesty

──There’s a perception out there that Mercari is a mission and value-driven organization. Do you feel that in your day-to-day work?

Narisawa: I had worked as both a project lead and product designer before, but actually, I had second thoughts beforehand.

I wondered if I could still fulfill my responsibilities as a product designer when I had to devote resources to a new job on top of that.

At that time, the CEO, Shintaro, told me one-on-one that our company has plenty of opportunities, so you should just do what you want to do. If it doesn’t work out, just go back to doing what you were before. His words really encouraged me.

In all sorts of situations in the course of developing the project, not just Shintaro, but other people in the management team told me to say whatever I want to, and they’ll back me up.
I was really grateful to be in that kind of an environment.

I feel that I have been able to hold onto my own principles as a product designer in my own way and expand my scope of activities.

Yokota: In that sense, I think that the management team believes that the most productive environment is one where everyone can do their own thing and use their own strengths.

That’s why we have an organization that allows top performers to do what they do best, rather than conforming to the lowest common denominator. We often say, “don’t do business with an information gap,” and we have an open culture here where it’s easy to gather information.

──Marcari’s working culture is one of it’s defining features. What kind of people are best suited for product development at Mercari?

Narisawa: I would say someone who hasn’t fully committed to any one area of expertise. Mercari is one product, but the way we communicate with customers changes every time we add new functions, so the way you organize that output the role you play in your work will also change.

You need to keep making adjustments. Today I’m doing product management work; tomorrow I might be doing engineering.

A lot of things happen every day in the product, and apps are created by having different people taking on different things.

People who can keep pace with that kind of production culture. Personally, I think people who aren’t too particular—in a good way—are the best fit for this company.

Yokota: I think that Mercari has a culture that values honesty.

At Mercari, you can see the conversations of other members over Slack, and it has a very open and friendly atmosphere.

People who feel constrained by black-box decision-making or having their individual will ignored. In other words, people who are honest and strong willed will find Mercari’s open environment very easy to work in and perform well in.

From a flea market app to an infrastructure app

──Where do you think the Mercari app is headed?

Yokota: From the outside, it might seem like that the Mercari app is already complete, but for both Japan and for the world, it’s not quite there yet.

There are still many people who don’t know what Mercari is, and there are still many potential future customers.

In order for Mercari to become a piece of social infrastructure, our employees need to broaden their horizons and continue to be comfortable trying new things in different domains.

The goals we have are big, and it feels like we haven’t reached the end of our mission at all.

I also feel like we tend to focus on evaluating short-term numbers and functions that are easy to verbalize and visualize. Emotional value seems to be less of a priority. Of course, short-term numbers are important, but I want to keep placing equal importance on non-verbal experiences and sensitivity.

Narisawa: Many people today think of Mercari as just a flea market app. There are still many customers who don’t know that it’s more than just buying and selling, they can also use credit and find a lot of ways to use the proceeds from sales.

For example, you can use your Merpay credit line to buy tools for your hobby on Mercari, even if you don’t have much money on hand. Then you can go out to a café and pay with Merpay, and then go and sell those tools back on Mercari when you buy new tools and don’t need the old ones anymore. This is how the Mercari app can help you do everything you want to do, all inside of one app.

I want to create a world where Mercari is considered an infrastructure app, and do that through dialogue with our customers. Right now we’re only a small percept of the way there.

Given 100 customers, there are going to be 100 different paths to take. We’re taking it a step at a time, improving every day to create those paths.

Contributor: Kayo Murakami
Photographer: Daisuke Koike
Design: Kirika Kosuzu
Editor: Michiko Kashimoto, Eiji Nogaki
Mercari | NewsPicks Brand Design
Production: NewsPicks Brand Design

Related Links Quick Reads ✨

Mercari Now Listed on the Prime Market Segment of the Tokyo Stock Exchange! #MercariDays

Mercari is establishing a new Center of Excellence in Bengaluru, India this summer! #Mercariindia #MercariDays

Taking a virtual tour inside Mercari’s Tokyo Office! Presented by: Mercari’s Onboarding Team! #Mercari Days

Related Links In-Depth Features ✨